
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Lesson 2.2.2</title>
</head>
<body>
<script>
  var Book = function (id, bookname, price) {
    this.id = id;
    this.bookname = bookname;
    this.price = price;
  }
  Book.prototype.display = function () {
    //展示这本书
  }
  var book = new Book();
  console.log(book.__proto__ == Book.prototype); //true
  console.log(book.__proto__.constructor == Book); //true
</script>
</body>
</html>